Have you seen Singin' in the Rain? It's a fictional story about the very real upheaval that occurred during Hollywood's last great paradigm shift, when films that had been silent suddenly found their voice, and performers who couldn't cope with the combination of emoting and speaking at the same time -- or those whose voices were less than melodious -- suddenly found themselves unemployable.

That first talkie was 1927's The Jazz Singer, and it heralded the almost instantaneous death of silent movies. I think we will look back at 300 in much the same way: as the harbinger of a new era in filmmaking, one that perhaps will not be quite so profound as the end of the silent era, but one that will redefine how we look at film ... and might leave some old-school actors behind in the process.

It's like this: CGI has been a tool in the filmmaker's toolbox for more than a decade now, but it's been used, for the most part, to create spaces and elements within those spaces that are meant to be "real." No matter how fantastical the element, whether it's the liquid-metal T-1000 Terminator or the sad, twisted figure of Gollum, it is meant to be taken as it appears: as genuine, authentic, something that really is what it looks like. Even when entire worlds are invented -- as in the recent Star Wars prequel trilogy -- and exist nowhere but in the filmmaker's imagination and then in a computer, they are meant to represent real buildings, real cities, real landscapes.

But 300 uses CGI in a new way, to create a world that is figurative (even more so than Sin City a few years ago). It brings a new kind of visual metaphor to film that only CGI could achieve, to generate an environment that is felt as much as, if not more than, seen and heard. The impossibly huge moon rising behind the bluff Leonidas climbs to visit the lecherous old priests and their captive oracle early in the film, for instance, is not a "real" moon -- it's a representation of how concepts of changeability and mysterious power hovered over the ancients, especially through their mythology. It's a representation of danger, of the night, of the unknown. We're not meant to believe the moon ever actually appeared so large over Sparta -- we're meant to feel the influence of what it represents to the Spartan people.

And under this filmmaking ethos -- more impressionistic than we've ever seen in a film that is not entirely animated -- what the cast brings is as much a puzzle piece of an element as the visuals. Which doesn't mean the actors only need to look right to fit into the overall tapestry -- paradoxically, it requires a different kind of acting ... one that some film actors working today may not be able to bring. Acting in front of a green screen leaves actors with few of the visual cues that working on location or on a fully constructed set provides. (Only one shot of 300 was filmed on location, that of the horses approaching Sparta in the beginning of the film; everything else was shot on a soundstage with minimal sets and props.) All that's left are the actors one is playing against, turning this into something more like stage acting ... and yet it's still as intimate as film acting, too, with the camera right in one's face and demanding carefully modulated performances even as one knows that what will eventually appear around you on the big screen may be larger than life, or odder than life. And this new kind of acting may also demand, as 300 did of its cast, that actors mold their bodies to fit the visual aesthetic even more so than we're used to hearing about. This wasn't Renee Zellweger gaining 30 pounds to play Bridget Jones -- this was a band of actors being turned into a regiment of soldiers, sculpting their bodies into visual metaphors as well. (Oh, and the near nudity of the men? That's a metaphor, too. Of course Spartan soldiers didn't fight in leather Speedos and nothing else; what we have here are those Spartan soldiers reduced to nothing more than their fighting prowess, in a figurative way.)

We're already seeing many film critics unable to get their heads about the impressionism of 300. There will be many actors who won't be able to make that transition either. They'll be okay -- nonimpressionistic movies aren't going away, and plenty of films will continue to be shot on location and with a grounded sense of the real. But as soon as other imaginative filmmakers come to grips with the sudden widening in the range of stories that can be told as 300's is told, we're going to see a whole new kind of film being made, ones that are more painterly than we've ever seen before.